[unreadable] Symptomatic urinary stone disease affects approximately 900,000 persons in the United States each year, resulting in an estimated annual medical cost of $4.5 billion. Computed tomography (CT) is the established method for imaging urinary calculi and can provide accurate sub-millimeter details of the size and location of renal stones. However, in clinical routine, even the most modern CT system cannot reliably determine stone composition or quantify the amount of stone material. [unreadable] Our long term goal is to use advanced CT methodologies to quantitate the morphology and composition of urinary calculi for the purpose of directing clinical treatment and facilitating clinical investigation. We plan to use available and evolving technology to reliably detect the smallest possible stones and/or stone precursor plaques. Our objective in this application is to develop accurate and reproducible non-invasive CT imaging tools to stratify patients into treatment groups according to stone composition and burden. Based on our extensive preliminary results, our central hypothesis is that dual-energy CT can discriminate several types of renal stones (e.g., uric acid vs. cystine vs. struvite vs. calcium-based stones) and provide accurate quantification of stone burden. Furthermore, we hypothesize that this quantitative assessment of stone composition and burden can be performed using iodine-enhanced dual-energy CT data, which presents an opportunity to reduce patient radiation dose compared to a traditional CT urogram. [unreadable] Our Specific Aims are: Aim 1: Develop a dual-energy CT imaging technique to discriminate between renal stones of different mineral composition. Aim 2: Reliably and accurately quantitate stone burden using dual-energy CT. Aim 3: Develop a method for stone characterization in the presence of iodinated contrast material. This proposal will develop imaging techniques that allow simultaneous identification of urinary stone type and quantification of stone burden, even in the presence of iodinated contrast material. The significance of this is that these advanced CT imaging techniques will allow physicians to more efficiently direct patient therapy and phenotype research subjects, potentially avoiding procedures associated with higher risk or cost. [unreadable] [unreadable]